linux-kernel - Re: [PATCH 2/2] scsi: virtio_scsi: limit number of hw queues by nr_cpu

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20190410131228.GB8210@stefanha-x1.localdomain>
Date:   Wed, 10 Apr 2019 14:12:28 +0100
From:   Stefan Hajnoczi <stefanha@...hat.com>
To:     Dongli Zhang <dongli.zhang@...cle.com>
Cc:     linux-scsi@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        linux-block@...r.kernel.org, mst@...hat.com, jasowang@...hat.com,
        axboe@...nel.dk, jejb@...ux.ibm.com, martin.petersen@...cle.com,
        cohuck@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] scsi: virtio_scsi: limit number of hw queues by
 nr_cpu_ids

On Wed, Mar 27, 2019 at 06:36:35PM +0800, Dongli Zhang wrote:
> When tag_set->nr_maps is 1, the block layer limits the number of hw queues
> by nr_cpu_ids. No matter how many hw queues are used by virtio-scsi, as it
> has (tag_set->nr_maps == 1), it can use at most nr_cpu_ids hw queues.
> 
> In addition, specifically for pci scenario, when the 'num_queues' specified
> by qemu is more than maxcpus, virtio-scsi would not be able to allocate
> more than maxcpus vectors in order to have a vector for each queue. As a
> result, it falls back into MSI-X with one vector for config and one shared
> for queues.
> 
> Considering above reasons, this patch limits the number of hw queues used
> by virtio-scsi by nr_cpu_ids.
> 
> Signed-off-by: Dongli Zhang <dongli.zhang@...cle.com>
> ---
>  drivers/scsi/virtio_scsi.c | 1 +
>  1 file changed, 1 insertion(+)

Reviewed-by: Stefan Hajnoczi <stefanha@...hat.com>

Download attachment "signature.asc" of type "application/pgp-signature" (456 bytes)